Catalytic cracking process using externally introduced carbon particles

ABSTRACT

A process for producing valuable products including gasoline and jet fuel by catalytic cracking with an acidic catalyst wherein the catalyst activity is improved and the selectivity of the catalyst for production of various C.sub.5 + product cuts is increased by carrying out the catalytic cracking process in the presence of dispersed carbon particles added to the reaction zone. Preferably, the particles are added to the hydrocarbon feedstock and dispersed therein prior to contacting the feedstock with the catalytic cracking catalyst in the reaction zone.

United States Patent [191 [I11 3,876,526

Mulaskey et al. 5] Apr. 8, 1975 CATALYTIC CRACKING PROCESS USING 2.906.692 9/1959 Baker et a1. 208/74 EXTERNALLY INTRODUCED CARBON PARTICLES 5:6 12:657 2/1972 Wennerberg et a1. 1. 252/425 [75] Inventors; Bernard F. Mulaskey, Fairfax; 3.715.303 2/1973 Wennerberg et a1. 208/112 R. Bose, Pleasant both Snyder of Calif- OTHER PUBLICATIONS [73] Assigneez Chevron Research Company, San Greensfelder et al., Catalytic and Thermal Cracking Francisco, Calif. of Pure Hydrocarbons, 1EC., Nov. 1949, pp.

9 [22] Filed: June 10, 1974 2584' [21] Appl. No.: 478,019 Primary E.\'aminerDelbert E. Gantz Assistant E.\'aminerG. E. Schmitkons Related Apphcatlon Data Attorney, Agent, or FirmG. F. Magdeburger; R. H. [63] Continuation-impart of Ser. No. 372.118, June 21. D i

1973 abandoned.

57 ABSTRACT [52] US. Cl. 208/113; 208/119; 208/120; 1

2O8/l27 208/146 A process for producmg valuable products Including Int Cl C10 l3/l8 9/00 gasoline and et fuel by catalytic cracking with an 158] Field 120 127 14 cidic catalyst wherein the catalyst activity is im- 208/119 252/444 446 447 proved and the selectivity of the catalyst for production of various C product cuts is increased by carry- [56] References Cited 1 ing out the catalytic cracking process in the presence of dispersed carbon particles added to the reaction UNTED STATES PATENTS zone. Preferably, the particles are added to the hydro- 2.387,088 10/1945 8t carbon feedstock and dispersed therein prior to cong i et tacting the feedstock with the catalytic cracking cataec erger 1 st in the reaction zone.

1859,17 1 11/1958 Adams et 81 208/114 y 2,865,846 12/1958 Degnen 208/147 7 Claims, N0 Drawings CATALYTIC CRACKING PROCESS USING EXTERNALLY INTRODUCED CARBON PARTICLES CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of US. application Ser. No. 372,118, filed June 2l, 1973. now abandoned, the disclosure of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION The ever-growing demand for crude oil coupled with the diminishing supplies has created an energy crisis. In view of the present situation, the necessity for squeezing the maximum amount of energy out of each barrel of crude is obvious.

This invention is directed to a process for improving conventional catalytic cracking processes to more closely approach that optimum.

DESCRIPTION OF THE PRIOR ART The use of activated carbon. a highly active, nonacidic catalyst, for cracking of hydrocarbons is not new. See. for example, the article titled Catalytic and Thermal Cracking of Pure Hydrocarbons" appearing in the November 1949 issue oflndustrial and Engineering Chemistry. The combination, however, of carbon particles with a conventional acidic cracking catalyst in the method described hereinafter is believed to be new.

SUMMARY OF THE INVENTION The subject invention is directed to cracking of a hydrocarbon feedstock in a catalytic cracking zone by contact with an acidic cracking catalyst in the presence of carbon particles which have been either added to the hydrocarbon feedstock prior to introduction of the feedstock into the catalytic cracking zone or have been introduced into the catalytic cracking zone concurrently with the hydrocarbon feedstock. Preferably, the carbon particles are added to the hydrocarbon feedstock and suspended therein. The carbon particles. preferably in the form of petroleum coke or charcoal, are dispersed in the feedstock in an effective amount generally ranging from 0.1 to 10. preferably 0.5 to 7 weight percent, based on the combined weight of the feedstock and the carbon particles.

DETAILED DESCRIPTION OF THE INVENTION As discussed above under SUMMARY OF THE IN- VENTION. the subject invention is directed to a process for catalytically cracking a hydrocarbon feedstock in the presence of dispersed carbon particles purposely added to the reaction zone. By the process of this invention, increased gasoline and jet fuel yields, without the concurrent increased gas yield normally attributed to increased conversion levels, may be obtained. Additionally, the activity of the catalyst is improved.

The process of this invention utilizes conventional hydrocarbon feedstocks to catalytic cracking zones, conventional acidic catalytic cracking catalysts, and conventional catalytic cracking conditions. This invention is directed to the improvement of carrying out the catalytic cracking process step in the presence of externally introduced carbon particles; that is, in the presence of carbon particles which have been either (1) purposely dispersed in the hydrocarbon feedstock prior to contacting said feedstock with the catalytic cracking catalyst, or (2) have been purposely introduced into the catalytic cracking zone concurrently with the introduction of the hydrocarbon feedstock to the catalytic cracking zone.

By the process of the subject invention, as will become clear by consideration of the examples. catalyst activity is increased and the selectivity of the catalyst for producing various C (defined as hydrocarbons having five or more carbon atoms) product cuts is increased.

CATALYTIC CRACKING CATALYSTS The acidic catalysts used in the catalytic cracking zone in the process of the present invention are those conventionally utilized in catalytic cracking processes. For example. activated, naturally occurring acidic catalytic cracking catalysts such as clay, i.e., kaolin. can be used. Synthetically prepared acidic cracking catalysts containing amorphous silica-alumina, with or without additional promoters, can also be used. as well as semisynthetic catalysts such as kaolin-silica-alumina composites. Zeolite-containing catalysts may also be used to reduce coke formation on the catalyst particles and to increase catalyst activity. Methods of preparation of amorphous catalytic cracking catalysts are well known. The crystalline zeolitic molecular sieve catalysts are disclosed and discussed in great detail in US. Pat. Nos. 3.2l0,267 and 3.271.418.

It should be recognized that different hydrocarbon feeds to the catalytic cracker present different problems and the catalyst used will in general be tailored to fit the particular needs of the hydrocarbon feedstock being used.

OPERATING CONDITIONS IN THE CATALYTIC CRACKING ZONE The temperature of the inlet of the catalytic cracking zone will generally fall within the range from about 700F. to about 1250F. more preferably 850 to l lO0F., with a conversion level of from 40 to on a volume basis. The pressure within the zones will generally fall within the range from about I to about psig, preferably 5 to 25, more preferably 15 to 20. The liquid hourly space velocities within the catalytic cracking zone will generally fall within the range from about 0.5 to about 50, although it can be as high as 100 or even higher. More generally, the space velocity within the catalytic cracking zone will fall within the range from about 2 to about 20. The preferred temperatures for use in the catalytic cracking zone will generally fall within the range from about 850F. to about 1050F., preferably 925 to 975F.

The catalytic cracking of the present invention may be performed utilizing well-known techniques, including. for example, fluidized bed or moving bed processes. Regeneration of the catalyst can be carried out using conventional regeneration techniques.

The hydrocarbon feedstock useful in the present invention will generally boil above about 400F., preferably in the range from about 450F. to about lO00F.; and more preferably 600 to l000F. The hydrocarbon feedstocks may include, for example, light and heavy gas oils obtained from atmospheric distillation, vacuum distillation and coker gas oils. The reaction conditions can be adjusted in the cracking zone according to the conversion level desired.

was carried out in a fixed bed using a standard S-minute cracking cycle. Various quantities and types of carbon particles were combined with the feedstock prior to contacting the feedstock with the catalyst. as indicated in Table 11. A liquid hourly space velocity on a weight basis of 3 was used for all runs. The results are shown in Tables 11 and 111.

TABLE I into the catalytic cracking zone concurrently with the 10 introduction of the hydrocarbon feedstock. The size of FEEDSTOCK HEAVY GAS 011. the carbon particleswill generally lie in the range of G QAPI n 7 I ravity. 40-90 microns. The quantity carbon particles used Aniline pom within the general range specified above W111 vary de- Sulfur. Wt. 91 0.77 Nitrogen. Wt. )1 0.29 pendent on the feedstock. natureof the carbon partil Ramsbmmm Carbon (H9 cles. operating conditions and desIred products. Petro- Pour Point. F. +75 leum coke and activated carb m. a

p l that de ASTM D1ST1LLAT1ON. F rived from coconuts. are particularly desirable carbon SOUI'CS. Start 455 It should be noted that coke buildup on an acidic catalyst utilized in conventional catalytic cracking pro- 309; 658 cesses occurs during the process operation. The subject invention utilizes discrete carbon particles introduced 9 937 from an external source. The coke buildup occurring 966 I B1. 972 on the acidic catalyst particles ser\ es to decrease cata- TABLE II CARBON LIGHT TOTAL MIDDLE PARTICLES Wt. 7t 7t GASOLINE JET FUEL GASOLINE DISTILLATE RUN ADDED TO CARBON CATA- CONVER- C -,300F. 300500F. C5430F. 430625F.

LYST NO. FEEDSTOCK PARTICLES (1) TEMP. SION (2) WT. 7r (3) WT. 71 (3) WT. 7t (3) WT. 71 (3) I none 0 927 68.3 26.5 21.6 40.0 22.7 2 (4) Charcoal 0.7 855 60.4 24.0 25.1 39.9 26.0 3 (4) charcoal 6.6 904 82.7 36.5 23.7 52.2 19.7 4 (5) coke 0.5 923 60.6 21.4 21.6 35.1 23.8 5 (5) coke 5.0 911 62.0 25.7 22.2 38.1 25.5

(1) Added to feedstock based on combined weight of particles and feedstock.

(2) On weight basis to materials boiling belotv 500F.. i.e.. (weight of 500F. product 1 weight of feed) X 100. 13) Wt. t of this particular product to fresh feed. (not including Carbon particles added to feed).

t-lt Activated coconut churcnnl with a surface area of greater than 80 m-/2. (5) Petroleum coke with a surface area of 1-10 in /g.

lyst activity. while the carbon particles introduced into the system by the process of the subject invention increase catalyst activity and selectivity. as noted in the following examples, which are offered by way of illustration and not by way of limitation.

EXAMPLES As can be seen from the data set forth in Table II. the catalytic cracking catalyst used in conjunction with 6.6% charcoal in the feedstock gave an 82.7% conversion rate at a catalyst temperature of 904F. This is in contrast to the conversion level of 68.3% at 927F. for the same catalyst without the addition of carbon particles to the feedstock. The product distribution and quantities was also higher for the coke containing feedstock. Coke was not as effective in increasing catalyst activity. However. the coke was effective in increasing middle distillate yield.

The amount of gas produced and its analysis for each of the five runs is shown in Table 111.

TABLE 111 -Cntinued GAS YlELDS 3 RUN NO. I 2 4 Cis-Z-Butcne 0.72 0.52 0.59 0.50 0.67 Trans-Z-Butenc 1.01 0.73 0.82 0.71 0.95 Total"-" C,- 1833 12.11 11.54 10.73 13.37

Wt. to Fresh Feed "Fresh feed does not include carbon added thereto.

means hydrocarbon gases having four or less carbon atoms.

As can be seen from Table 111. the amount of gas produced was dramatically lower using the processof this invention.

The conversion of the feedstock to olefinic materials is shown in Table IV.

TABLE IV Run Ratio Wt. 71" Ratio Wt 21 'Ratio equals weight ol'nlelin X 100 (weight of olefin plus weight ofparat'fin with same number of carbon atoms) "Wt. olefin to fresh l'ccd.

As can be seen from Table IV, the yield quantities of C C olefins are reduced by the selectivity of the cat alyst being shifted to heavier hydrocarbons boiling in the gasoline range.

It is apparent that many widely different embodiments of this invention may be made without departing from the scope and spirit thereof; and, therefore. it is not intended to be limited except as indicated in the appended claims.

lytic cracking catalyst.

3. The process of claim 1 wherein said carbon particles are introduced into said catalytic cracking zone concurrently with said hydrocarbon feedstock.

4. The process of claim 1 wherein said carbon particles are present in an amount of from 0.1 to 10 weight percent based on the combined weight of said feedstock and said carbon particles.

5. The process of claim 1 wherein said carbon particles are present in an amount of from 0.5 to 7 weight percent based on the combined Weight of said feedstock and said carbon particles.

6. The process of claim 1 wherein said carbon particles are petroleum coke.

7. The process of claim 1 wherein said carbon particles are activated charcoal. 

1. IN A PROCESS WHEREIN A HYDROCARBON FEEDSTOCK IS CATALYTICALLY CRACKER BY CONTACTING SAID FEEDSTOCK WITH AN ACIDIC CATALYTIC CRACKING CATALYST IN A CATALYST CRACKING ZONE, THE IMPROVEMENT WHICH COMPRISES CRACKING SAID FEEDSTOCK IN THE PRESENCE OF AN EFFECTIVE AMOUNT OF DISPERSED CARBON PARTICLES ADDED TO SAID REACTION ZONE.
 2. The process of claim 1 wherein said carbon particles are added to said feedstock and dispersed therein prior to contacting said feedstock with said acidic catalytic cracking catalyst.
 3. The process of claim 1 wherein said carbon particles are introduced into said catalytic cracking zone concurrently with said hydrocarbon feedstock.
 4. The process of claim 1 wherein said carbon particles are present in an amount of from 0.1 to 10 weight percent based on the combined weight of said feedstock and said carbon particles.
 5. The process of claim 1 wherein said carbon particles are present in an amount of from 0.5 to 7 weight percent based on the combined weight of said feedstock and said carbon particles.
 6. The process of claim 1 wherein said carbon particles are petroleum coke.
 7. The process of claim 1 wherein said carbon particles are activated charcoal. 